A unified neural-network-based speaker localization technique

Locating and tracking a speaker in real time using microphone arrays is important in many applications such as hands-free video conferencing, speech processing in large rooms, and acoustic echo cancellation. A speaker can be moving from the far field to the near field of the array, or vice versa. Many neural-network-based localization techniques exist, but they are applicable to either far-field or near-field sources, and are computationally intensive for real-time speaker localization applications because of the wide-band nature of the speech. We propose a unified neural-network-based source localization technique, which is simultaneously applicable to wide-band and narrow-band signal sources that are in the far field or near field of a microphone array. The technique exploits a multilayer perceptron feedforward neural network structure and forms the feature vectors by computing the normalized instantaneous cross-power spectrum samples between adjacent pairs of sensors. Simulation results indicate that our technique is able to locate a source with an absolute error of less than 3.5 degrees at a signal-to-noise ratio of 20 dB and a sampling rate of 8000 Hz at each sensor.

Retropharyngeal submucosal dissection due to nasotracheal intubation

PROBLEM

Nasal intubation is used often by anaesthetists because it offers many advantages; however, rare complications do arise. A 67-year-old man was admitted to our otorhinolaryngology clinic for uvulopalatopharyngoplasty. Nasotracheal intubation was performed without difficulty. At the beginning of surgery, the surgeon noticed that the nasotracheal tube had penetrated the oropharyngeal mucosa through a channel in the retropharyngeal space.

METHODOLOGY

The tube was left in place during surgery to prevent bleeding. After surgery, a vertical incision was made through the mucosa surrounding the tube from the inferior pouch up to the nasopharynx to prevent hematoma.

RESULT

The patient was extubated without complication and discharged on the second day postoperative. The oropharyngeal mucosa was healed by the 15th day postoperative.

CONCLUSION

Nasal intubation tubes should be lubricated and inserted without force; the oropharynx should be examined carefully after intubation to rule out complications.

Preventable thermal burns associated with the ignition of paint thinner: experience of a burn care network in Turkey

AIM

This retrospective study evaluated the epidemiology of burn injuries, due to paint thinner ignition, in patients treated at the burn units of a university hospital network.

METHODS

From 1997 to 2005, 28 patients with thermal burns caused by ignition of paint thinner were admitted to our burn units. Age, sex, etiologic factors, extent and localization of burns, length of hospitalization, outcomes compared with other causes of thermal burns, and mortality rates were recorded for each patient.

RESULTS

There were 25 males and 3 females. Mean age of the patients was 27.88+/-14.74 years. Two patients (7.4%) came from rural regions; the majority (92.9%; n=26) lived within city boundaries. The most common etiologic factor was attempting to start a fire in the stove with paint thinner. Mean extent of burns was 48.82+/-27.39% of the total body surface area. When compared with other flame burn causes, the extent of burns was significantly greater in paint-thinner burn patients. Affected body sites, in order of most affected to least affected, were the hands, feet, head and face, neck, and trunk and genital regions. Mean length of hospitalization for survivors was 39.65+/-37.83 days. The overall mortality rate was 39.3%. Sepsis (63.6%), excessive burns with inhalation injury (18.2%), pulmonary embolism (9.1%), and respiratory failure (9.1%) were the causes of the deaths.

CONCLUSION

Paint thinner ignition may cause excessive burns with high mortality rates. Its common misuse in starting stove fires by persons living in urban areas should be prevented immediately.

Duct-to-duct biliary reconstruction in pediatric liver transplantation: one center's results

In pediatric liver transplantation, both for cadaveric and living-related patients, the Roux-en-Y hepaticojejunostomy is often preferable to biliary reconstruction. Duct-to-duct biliary reconstruction in pediatric patients has been utilized only in a limited numbers of studies. Here, we retrospectively review our experience with duct-to-duct biliary reconstruction in pediatric liver transplantation patients. Since September 2001, 46 liver transplantations have been performed in 44 patients (29 boys and 15 girls of mean age, 8.4 +/- 5.5 years). For the anastomoses, a corner-saving suture technique was used with 6-0 or 7-0 polypropylene monofilament nonabsorbable suture. A T tube was used in three patients, and in 11 patients, a straight feeding tube was inserted from the recipient common bile duct to the anastomotic site. A transhepatic biliary catheter insertion technique was used in 28 patients for external bile drainage; the remaining four patients had no tubes or stents. Four patients developed bile leakage in the early postoperative period. Three of these patients were treated with percutaneous drainage with excellent outcomes; the remaining patient required reoperation with a Roux-en-Y hepaticojejunostomy for bile leakage. Four biliary stenoses occurred in the late postoperative period. All biliary stenoses were successfully treated with balloon dilatation. There was no mortality or graft loss due to biliary complications. Of the 44 original patients, 36 (82%) are well at this time, with optimal liver function during follow-up (2-34 months). The remaining eight (18%) died during the study from acute respiratory distress syndrome (n=2), sepsis with multiorgan failure (n=5), and intracranial bleeding (n=1). Our results showed that duct-to-duct biliary reconstruction is a safe and easy technique for pediatric patients.

Pediatric Liver Transplantation for Acute Liver Failure

The only proven therapy for patients unlikely to recover from acute liver failure (ALF) is liver transplantation. Correct diagnosis of these individuals and rapid referral to a transplant center are crucial. We evaluated 12 pediatric patients with ALF who underwent liver transplantation (LT) at our institution during a 3-year period. The reasons for transplantation were hepatitis A (3 patients); non-A, non-E hepatitis (3); autoimmune hepatitis (1); fulminant Wilson's disease (3); Amanita phalloides (mushroom) poisoning (1); and hepatitis B and toxic hepatitis with leflunomide treatment (1). Seven of the participants were female and five were male (mean age, 9.1 +/- 4.2 years). Three received right liver-lobe grafts, one received a whole liver graft, and the remainder received left or left-lateral liver lobe grafts. All patients recovered from hepatic coma the second postoperative day. Two patients died at postoperative days 57 and 71 due to adult respiratory distress syndrome and sepsis with multiorgan failure, respectively. One patient required retransplantation because of chronic rejection 7 months after the initial transplantation. That patient died 10 days after retransplantation because of sepsis. Nine patients were healthy at follow-up (range, 2-46 months). LT is the only treatment option for ALF in patients in countries with low organ-donation rates. In this scenario, donor preparation in a limited time frame is difficult. We have been able to decrease the duration of donor preparation to approximately 4 hours (including biopsy of the donated liver tissue).

Predictors of Immediate Tracheal Extubation in the Operating Room After Liver Transplantation

Immediate postoperative extubation may reduce the incidence of postoperative respiratory complications after orthotopic liver transplantation (OLT). We evaluated the predictors of immediate tracheal extubation in the operating room (OR) in our patients by retrospectively reviewing data from all patients who underwent OLT between January 2004 and June 2006. The patients were divided into two groups according to whether they had undergone extubation in the OR (group 1 n=52) or in the intensive care unit (ICU; group 2 n=48). When compared with the patients in group 2, those in group 1 had lower mean preoperative serum creatinine levels (0.9 +/- 1 vs 0.6 +/- 0.3 mg/dL, P=.04) and intraoperative transfusion requirements (packed red blood cells, 35.5 +/- 29.8 vs 25.6 +/- 19.0 mL/kg; P=.05, and fresh frozen plasma, 33.1 +/- 15.6 vs 25.7 +/- 14.3 mL/kg; P=.01). The incidence of intraoperative hypotension and emergent OLT was significantly greater in group 2 than group 1 (33.3% vs 13.5%, P=.01 and 45.8% vs 21.2%, respectively, P=.009). On logistic regression analysis, only emergent OLT (P=.009, odds ratio = 3.5) and intraoperative hypotension (P=.018, odds ratio = 3.7) were significantly associated with a lower probability of immediate postoperative extubation in the OR. Our results suggested that hemodynamic stability and elective OLT were predictors of successful immediate tracheal extubation in the OR.

Effect of the Interval Between Organ Donor Brain Death and Organ Harvesting on Kidney Graft Function After Transplantation

We hypothesized that providing a longer resuscitation period (>12 hours) for a brain-dead organ donor (BDOD) to attenuate the detrimental effects of sympathetic discharge that occur during this event would improve graft function. We reviewed the medical records of patients who had received a kidney transplant from a BDOD between November 2001 and June 2006. The patients were divided into two groups according to whether the interval between the brain death of the organ donor and organ harvest was >12 hours (group 1 n=12) or <or=12 hours (group 2 n=11). The BDODs for the patients in the two groups displayed similar blood urea nitrogen (BUN) and creatinine levels during the interval between brain death and organ harvest. The graft recipients showed similar levels of serum creatinine. BUN, and urine output at baseline and on postoperative day 1 (P>.05). When compared with patients in group 2, those in group 1 demonstrated a significant trend toward improved renal graft function in terms of serum creatinine levels, BUN levels, and urine output. Five patients in group 2 and two patients in group 1 required hemodialysis during the early posttransplantation period (P>.05). Our results indicate that longer in situ resuscitation of the graft kidney in BDODs may improve posttransplant function.

Lung cancer detection with low-dose spiral computed tomography in chronic obstructive pulmonary disease patients

PURPOSE

To determine whether low-dose spiral computed tomography (LDCT) can improve the lung cancer detection rate in chronic obstructive pulmonary disease (COPD) subjects.

MATERIAL AND METHODS

From October 1999 to December 2003, 374 COPD patients underwent LDCT for lung carcinoma screening. All subjects with an abnormal baseline CT scan were followed with serial CT scans as part of our protocol. Follow-up was continued until the demonstration of no change over a minimum of 24 months, or resolution. Sputum samples were also obtained for cytological analysis.

RESULTS

On the baseline spiral CT scan, 132 of 374 patients (35.2%) had at least one non-calcified nodule that required periodic follow-up with CT scans. The median follow-up time was 21 months (range 2-48 months). Of the 374 COPD subjects, nine patients with primary lung cancer (2.4%) were detected: six were squamous cell carcinomas, two were small-cell lung carcinomas (SCLC), and one was adenosquamous carcinoma. Three of the nine tumors were in stage IA, two in stage IIB, two in stage IIIA, and two were limited SCLC. Potentially curative pulmonary resection was performed in four patients, pulmonary lobectomy in three, and wedge excision in one. One subject with stage IA squamous cell carcinoma received radiotherapy, as pulmonary function was severely impaired. In addition, four patients underwent removal of benign lesions. Sputum was collected in 205 (54.8%) of 374 patients. There were 154 (75 %) metaplasia, 14 (6%) moderate dysplasia, and one (0.4%) malignant case.

CONCLUSION

LDCT increases early lung carcinoma detection rate in COPD patients, but pulmonary function impairment may reduce its benefit.

A comparison of pre-emptive analgesic efficacy of diflunisal and lornoxicam for postoperative pain management: a prospective, randomized, single-blind, crossover study

Diflunisal and lornoxicam are currently available non-steroidal anti-inflammatory drugs (NSAIDs) that have been shown to be effective to various degrees in pain relief when administered either pre-emptively or postoperatively. The pre-emptive analgesic efficacy of diflunisal 1000 mg was compared with that of lornoxicam 16 mg in 40 ASA I patients undergoing surgical removal of bilateral impacted third molars. The impacted third molar teeth on one side were removed at the first surgical appointment using one of the two drug regimens being assessed and the teeth on the contralateral side were removed at a second appointment using the alternate drug regimen; all operations were performed by the same surgeon. Acetaminophen up to 2000 mg daily was provided as rescue medication. The postoperative rescue analgesic consumption was recorded and pain scores were evaluated with a visual analogue scale at 2, 4, 6, 12 and 24h postoperatively. No statistically significant differences were found between groups with respect to rescue analgesic consumption and postoperative pain scores. Pre-emptive administration of both NSAIDs proved to be effective in the management of pain following the surgical removal of impacted third molar teeth.

Liver Transplantation in Children Weighing Less Than 10 Kilograms

Orthotopic liver transplantation (OLT) remains a major medical and surgical challenge in small pediatric patients. From April 2003 through October 2005, 17 infants (each of whom weighed less than 10 kg) underwent the procedure. Four were girls and 13 were boys (mean age, 15.7 +/- 9.3 months [range, 2-36 months]; mean weight at the time of transplantation, 7.4 +/- 2.6 kg [range, 6-10 kg]). All transplants were obtained from living-related donors. Sixteen left lateral segments and 1 left lobe were transplanted. The median graft-to-recipient weight ratio was 3.5% +/- 1.2% (range, 1.5%-6.1%). During the early postoperative period, hepatic arterial thrombosis was identified in 2 infants, and a biliary leak in 1. Hepatic arterial thrombosis was treated by reanastomosis with polytetrafluoroethylene grafting in the first patient and by surgical embolectomy in the second. The biliary leak was treated with percutaneous drainage. In 1 infant, portal vein stenosis, which was identified during the late postoperative period, was treated by percutaneous balloon dilatation. At this time, 14 (82.3%) infants were alive, exhibiting good graft function at a median follow-up of 11 months (range, 2-36 months). Three infants died: 1 on postoperative day 47 from adult respiratory distress syndrome, 1 on postoperative day 12 from sepsis, and 1 on postoperative day 65 from sepsis associated with EBV infection. Episodes of acute rejection, which occurred in 5 patients, were treated with pulse steroid therapy. On follow-up, histologic examination revealed hepatocellular carcinoma in 2 infants and Burkitt's lymphoma in 1 infant. Our data confirm that extensive use of living-related donors in liver transplantation can result in an excellent outcome for small pediatric patients.

Comparison of adsorption capacity of young brown coals and humic acids prepared from different coal mines in Anatolia

Binding of Zn2+ and Cd2+ cations to relatively young brown coals YBC (lignite), humic acids (HAs) and commercial humic acid (CHA) were studied in aqueous media at pH 2.7-6 by polarographic method. This study was conducted to evaluate the removal of heavy metals in an aquatic system without prior treatment. The general principles of cation binding to YBC and humic materials are discussed. Sorption of heavy metal ions (Zn2+ and Cd2+) on samples of YBCs from three areas (Ilgin, Beysehir, and Ermenek) in the vicinity of the city of Konya in Anatolia (Turkey) were compared with sorption of these metal ions on HAs, prepared from these YBCs. The ability of both types of sorbent to remove metals from aqueous solutions was studied as a function of pH and concentration of initial metal solutions. Sorption depends strongly on pH, the origin of the YBC and on the nature of the metal ion. Whereas, for YBCs the main ligand groups seem to be carboxylate ions, this is not the case for the HA polymers, prepared from three YBCs, which differ substantially from properties of commercial samples of "HA". The process is very efficient especially in the case of low concentrations of pollutants in water, where common methods are either economically unfavorable or technically complicated. Of the two metal ions examined, Cd2+ was found to form the most stable HA complexes, followed by Zn. Effective removal of metals was demonstrated at pH-values of 5-5.7. The adsorption isotherm was measured at 25 degrees C, using adsorptive solutions at the optimum pH-value to determine the adsorption capacity. An important aspect of the proposed method was that the removal was performed on several metals at a pH-range in which a given metal undergoes an adsorption process making the method useful for wastewater treatment.

Results of Biliary Reconstructions in Liver Transplantation at Our Center

Biliary complications are some of the most critical problems in liver transplantation. Despite various refinements in surgical technique, different types of liver transplantations are associated with significant numbers of biliary problems. In this study, we analyzed the results of biliary reconstructions in 127 liver transplant recipients at our center from April 2001 to May 2006. Through November 2004, we used different techniques for biliary reconstruction in 66 of these patients, including duct-to-duct (DD) anastomoses, Roux-en-Y hepaticojejunostomy (RYHJ), anastomoses over T tubes or stents, and anastomoses without stenting. During the first period, we used a DD anastomosis in 15 cadaveric whole liver grafts and in 25 right lobe and 12 left lobe or left lateral segment grafts from living-related donors. RYHJ was preferred in 2 cadaveric and 12 left lateral segment grafts. Beginning in November 2004, we employed intraoperative transhepatic biliary catheter insertion in 61 patients (29 children, 32 adults). In the most recent 61 cases of 13 liver grafts from cadavers and 48 from living-related donors, 14 patients (2 children and 12 adults) received whole-liver grafts, 22 (all adults) a right lobe, and 26 (all children) a left lateral or left lobe. Intraoperative transhepatic biliary catheter insertion was performed with DD anastomosis in 55 cases and with RYHJ in 6 cases. The mean complication rate decreased from 24% to 8.1% during the period using a new biliary reconstruction technique. Five biliary complications occurred in four patients. The new technique of biliary reconstruction using intraoperative biliary catheter insertion has significantly reduced the biliary complication rate. Transhepatic biliary stenting prevents biliary complications and maintains percutaneous access when problems arise. Intraoperative transhepatic biliary catheter insertion at the back table is a safe way to provide good biliary drainage after liver transplantation.

A corner-saving ureteral reimplantation technique without stenting

In this study we present our new technique, which will simplify reconstruction of even a small-caliber ureter. Our transplantation team has performed 1523 renal transplantation since 1975. From 1975 to 1983, we performed 300 ureteroneocystostomies using the modified Politano-Leadbetter technique. Since 1983, the extravesical Lich-Gregoir technique was used in combination with temporary ureteral stenting in 1141 patients. After September 2003, we began a corner-saving technique. Eighty-two (62 living related, 20 cadaver) renal transplantations have been performed since September 2003. The mean recipient age was 32.2 +/- 10.9 years (range, 7 to 63). Mean donor age was 38.9 +/- 13.1 years. For ureteral reimplantation, a running suture is started from 3 mm ahead from the middle of the posterior wall and finished 3 mm afterward. After the last stitch, both ends of the suture material are pulled and the posterior wall of the ureter and bladder are approximated tightly. The anterior wall is sewn either with the same suture or another running suture. Since using this technique, we have not employed a double J or any other stent to prevent ureteral complications at the anastomosis side. We have seen only two (2.4%) ureteral complications. In conclusion, due to the low complication rate, we believe that our new technique is the safest way to perform a ureteroneocyctostomy.

Respiratory Problems in Renal Transplant Recipients Admitted to Intensive Care During Long-Term Follow-Up

Cardiovascular disease, malignancies, and infectious complications are major causes of morbidity and mortality of renal transplant recipients. Mortality rates vary between 16% and 40% in an intensive care unit (ICU). The aims of this study were to identify the types incidences of respiratory problems that affected renal transplant recipients admitted to the ICU during long-term follow-up thereby determining the impact of respiratory problems on mortality. We reviewed the data for 34 recipients who had 39 ICU admissions from January 2000 through December 2003. Twenty-four admissions (61.5%) had at least one respiratory problem at admission or developed at least one during the ICU stay. The most frequent problem was pneumonia (n=18, 46.2% of the 39 readmissions), followed by acute respiratory failure (n=10, 25.6%), atelectasis (n=9, 23.1%), pleural effusion (n=8, 20.5%), and pulmonary edema (n=2, 5.1%). The patients who had respiratory problems showed a significantly higher mortality rate than those who did not have respiratory problems (66.6% versus 26.6%, respectively; P<.05). The overall mortality rate was 58.8% (20 patients). Thus, infectious and respiratory problems are the most frequent indications for admission and the most common problems during an ICU stay. The prognosis for patients who either have a respiratory problem upon admission to the ICU or develop one during the ICU stay is poor.